The present cooling system relates to the food industry, and more particularly, to a pan chiller system for providing uniform cooling to food pans provided in a food well.
In the food service industry, it is important to maintain food at desired temperatures in food pans to preserve food freshness. Accordingly, pan cooling/chilling systems have been developed, such as those disclosed in U.S. Pat. Nos. 5,355,687 and 5,927,092 and commonly-owned U.S. Provisional Patent Application No. 60/860,449, which are herein incorporated by reference in their entirety.
One problem experienced by current chilling systems is damage to the electrical components or wiring located within or in close proximity to the food pans due to condensation and/or spilled food dripping on the components or on the wiring. Excessive condensation especially results in cooling energy transfer inefficiency and possible premature component failure due to the extra work needed to achieve sufficient cooling.
For example, in many current systems, the generally copper tubing cooling element is provided below the food pans. Condensation on the relatively cold tubing results in frost forming on the tubing, reducing heat transfer efficiency of the system. To remove such frost, many current systems will periodically increase the temperature of the coolant within the tubing, causing the frost to melt and drip into the bottom of the unit, requiring disassembly of the unit for cleaning, which can cause damage to the wiring and increases system down time.
Also, current chilling systems generally are based on a Freon system that requires a change of state from liquid to gas to extract heat. Accordingly, they operate at a pressure of as much as 300 psi. This relatively high operating pressure requires expensive piping and fittings. A further issue in current chilling systems is their use of Freon as the coolant, which may be considered hazardous to the ozone layer if leaked to the atmosphere.
Another problem experienced by many current chilling systems is the inability to uniformly cool the food pans. Excessive or uneven cooling may damage many types of high moisture foods if the temperature drops below the freezing point of water, especially near the wall of the pan. One attempt to resolve this issue is to include a fan located in close proximity to the food pans for circulating air around an outside of the food pans in the sub-pan cooling unit. However, in practice, condensation and food spillage can result in damage to the fan and associated components.
Many current pan chilling systems utilize a cold-wall design, in which refrigeration lines are mounted in direct contact with the interior walls of the food well, and refrigerant is pumped through the lines. As the refrigerant evaporates, these interior walls serve as a heat sink for the enclosure surrounding the food pans. However, it has been found that in a cold-wall design, generally the pans around the perimeter of the food well opening are adequately cooled, but the coolant does not adequately chill the pans located in the center of the opening Attempts to adequately cool food located in the center of the pan and/or food well opening typically involves lowering the coolant temperature in these systems. However, while this may cool the food provided in the center of the opening, it can cause the food closer to the perimeter of the opening to freeze.
To reduce ice or frost build-up and operate efficiently, current pan chilling systems employ a defrost cycle generally once an hour or overnight. During the defrost cycle, the chilling system operates at a higher temperature to remove the frost build-up, which can reduce the performance of the system because the food pans generally need to be removed prior to the defrost cycle.
Accordingly, there is a need for an improved pan chilling system that addresses the inefficiencies caused by condensation and/or food spillage forming on the coolant lines, and that provides more uniform and efficient cooling to the entire system. In addition, there is a need for an improved chilling system employing a coolant that is relatively environmentally friendly. Further, there is a need for an improved chilling system that more efficiently cools the individual food pans. Also, there is a need for an improved chilling system that prevents condensation, ice or moisture buildup on and around the food pans and the food well. There is a further need for an improved chilling system that can be easily manufactured and modified to suit the application.